/*
 * $OpenBSD: readlink.c,v 1.28 2019/06/28 13:35:03 deraadt Exp $
 *
 * Copyright (c) 1997
 *	Kenneth Stailey (hereinafter referred to as the author)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "compat.h"

static void usage(void);

int main(int argc, char *argv[]) {
  setprogname(argv[0]);
  char buf[PATH_MAX];
  int n, ch, nflag = 0, fflag = 0;
  extern int optind;

  while ((ch = getopt(argc, argv, "fn")) != -1) switch (ch) {
      case 'f':
        fflag = 1;
        break;
      case 'n':
        nflag = 1;
        break;
      default:
        usage();
    }
  argc -= optind;
  argv += optind;

  if (argc != 1) usage();

  n = strlen(argv[0]);
  if (n > PATH_MAX - 1) {
    fprintf(stderr, "readlink: filename longer than PATH_MAX-1 (%d)\n",
            PATH_MAX - 1);
    exit(1);
  }

  if (fflag) {
    if (realpath(argv[0], buf) == NULL) err(1, "%s", argv[0]);
  } else {
    if ((n = readlink(argv[0], buf, sizeof buf - 1)) == -1) exit(1);
    buf[n] = '\0';
  }

  printf("%s", buf);
  if (!nflag) putchar('\n');
  exit(0);
}

static void usage(void) {
  (void)fprintf(stderr, "usage: readlink [-fn] file\n");
  exit(1);
}
